Gene expression analysis in sections and tissue microarrays of archival tissues by mRNA in situ hybridization

Altered expression of genes in diseased tissues can prognosticate a distinct natural progression of the disease as well as predict sensitivity or resistance to particular therapies. Archival tissues from patients with a known medical history and treatments are an invaluable resource to validate the utility of candidate genes for prognosis and prediction of therapy outcomes. However, stored tissues with associated long-term follow-up information typically are formalin-fixed, paraffin-embedded specimen and this can severely restrict the methods applicable for gene expression analysis. We report here on the utility of tissue microarrays (TMAs) that use valuable tissues sparingly and provide a platform for simultaneous analysis of gene expression in several hundred samples. In particular, we describe a stable method applicable to mRNA expression screening in such archival tissues. TMAs are constructed from sections of small drill cores, taken from tissue blocks of archival tissues and multiple samples can thus be arranged on a single microscope slide. We used mRNA in situ hybridization (ISH) on >500 full sections and >100 TMAs for >10 different cDNAs that yielded >10,000 data points. We provide detailed experimental protocols that can be implemented without major hurdles in a molecular pathology laboratory and discuss quantitative analysis and the advantages and limitations of ISH. We conclude that gene expression analysis in archival tissues by ISH is reliable and particularly useful when no protein detection methods are available for a candidate gene.     

基于转录调控模体的人不同组织基因差异性的统计分析

转录调控是基因表达调控的主要过程,而转录调控模体使用的差异性可能是导致基因组织特异性的因素之一.本文提出一种不同组织基因调控差异性的统计分析方法,首先结合泊松分布和主成分分析提取基因启动子中过表达模体作为潜在的转录因子结合位点.基于这些位点通过Wilcoxon秩和检验获得不同组织基因结构的差异性.再用超几何分布确定出现次数显著的模体作为组织基因的特有模体,并分析特有模体的碱基特征及在启动子序列中的位置分布.将特有模体与TRANSFAC数据库进行对照,得到潜在的调控组织特异性基因的转录因子结合位点.以人管家基因及30个组织特异性基因为分析对象,得到不同组织调控模体使用的差异性信息.